题目

下图是科学家对果蝇一条染色体上的基因进行测定的结果。下列说法中正确的是 A 控制朱红眼与深红眼的基因是等位基因 B 控制白眼和朱红眼的基因在遗传时遵循基因的自由组合定律 C 该染色体上基因控制的性状在后代中一定同时都会显现 D 基因在染色体上呈线性排列 答案：D---I saw Mr. Smith in the office at ten yesterday morning.---That’s impossible. He _______ an English party with us then.A. has B. had C. was having D. has had